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Viral Encephalitis

Updated : March 5, 2024





Background

Viral encephalitis is an inflammatory condition which affects the brain parenchyma. Viral encephalitis is prevalent kind of encephalitis, which is frequently associated with viral meningitis. In this condition, the affected patient is affected outside the CNS, and soon it spreads retrogradely from nerve endings to the brain and spinal cord.

Viral encephalitis seems is more prevalent in younger adults than in the elderly. Nevertheless, this also depends on the environment. Numerous instances of viral encephalitis aren’t detected due to a lack of serious symptoms and less testing. Certain studies demonstrate that most affected individuals develop significant amounts of virus-specific antibodies without manifesting any symptoms.

Epidemiology

Around 3.5-7.5 out of 100,000 individuals are annually affected with viral encephalitis. This condition is most prevalent in younger or older patients. In the past, encephalitis was commonly caused by mumps or measles, but that has significantly reduced over time. Instead, CMV and EBV encephalitis have become increasingly common because they mostly affected immunocompromised patients.

Patients undergoing chemotherapy, or patients who have had transplants are as likely to be affected as are patients who have AIDS. Other factors which can increase the risk for encephalitis include the location, time, and exposure to insects of animals. HSV is the leading cause of encephalitis in the United States.

Anatomy

Pathophysiology

Outside of the CNS, viruses enter the host and multiply. Most then travel hematogenically to the spinal cord and brain. HSV, rabies, and herpes zoster virus represent significant exceptions. They migrate retrograde from nerve terminals to the central nervous system.

Once the brain is affected, the virus and the inflammatory response of the host affect the function of neuronal cells. Normal gross examination findings include cerebral edoema, vascular congestion, and bleeding. Leukocyte or microglial cell infiltration is also a typical characteristic.

Necrosis can be extensive in patients with JE and EEE. Calcification is frequently observed following arbovirus encephalitis, especially in youngsters. Herpes simplex has a tendency to cause focal necrotic lesions with prominent intranuclear inclusions.

Etiology

Viral encephalitis is caused by viruses, bacteria, fungi, protozoa, or helminths. Despite intensive investigation, the cause of many episodes of encephalitis is unknown.

The most common known cause of encephalitis are viruses, accounting for around 70% of cases diagnosed.

The three most common causes of viral encephalitis are:

  • West Nile Virus
  • Herpes Simplex Virus
  • Enteroviruses

Dengue, rabies, western equine virus, rubella, cytomegalovirus, measles, mumps, varicella-zoster virus, and Epstein-Barr virus are among some other viral agents which cause viral encephalitis.

Genetics

Prognostic Factors

The majority of people with viral encephalitis experience a complication-free recovery. Those with persistent symptoms experience attention difficulties, behavioural and speech issues, and/or memory loss. Rarely, patients may continue to exist in a vegetative state. Some children infected with WEE may have convulsions and behavioural problems.

In the aftermath of EEE, children may experience seizures, severe mental retardation, and different types of paralysis. Infection with the Zika virus during pregnancy may be connected with microcephaly.

Seizures are the most prevalent long-term consequence following viral encephalitis, affecting 10-20% of individuals over decades. These convulsions are frequently resistant to medical treatment.

Clinical History

Physical Examination

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Medication

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References

https://www.ncbi.nlm.nih.gov/books/NBK470162/

Viral Encephalitis

Updated : March 5, 2024




Viral encephalitis is an inflammatory condition which affects the brain parenchyma. Viral encephalitis is prevalent kind of encephalitis, which is frequently associated with viral meningitis. In this condition, the affected patient is affected outside the CNS, and soon it spreads retrogradely from nerve endings to the brain and spinal cord.

Viral encephalitis seems is more prevalent in younger adults than in the elderly. Nevertheless, this also depends on the environment. Numerous instances of viral encephalitis aren’t detected due to a lack of serious symptoms and less testing. Certain studies demonstrate that most affected individuals develop significant amounts of virus-specific antibodies without manifesting any symptoms.

Around 3.5-7.5 out of 100,000 individuals are annually affected with viral encephalitis. This condition is most prevalent in younger or older patients. In the past, encephalitis was commonly caused by mumps or measles, but that has significantly reduced over time. Instead, CMV and EBV encephalitis have become increasingly common because they mostly affected immunocompromised patients.

Patients undergoing chemotherapy, or patients who have had transplants are as likely to be affected as are patients who have AIDS. Other factors which can increase the risk for encephalitis include the location, time, and exposure to insects of animals. HSV is the leading cause of encephalitis in the United States.

Outside of the CNS, viruses enter the host and multiply. Most then travel hematogenically to the spinal cord and brain. HSV, rabies, and herpes zoster virus represent significant exceptions. They migrate retrograde from nerve terminals to the central nervous system.

Once the brain is affected, the virus and the inflammatory response of the host affect the function of neuronal cells. Normal gross examination findings include cerebral edoema, vascular congestion, and bleeding. Leukocyte or microglial cell infiltration is also a typical characteristic.

Necrosis can be extensive in patients with JE and EEE. Calcification is frequently observed following arbovirus encephalitis, especially in youngsters. Herpes simplex has a tendency to cause focal necrotic lesions with prominent intranuclear inclusions.

Viral encephalitis is caused by viruses, bacteria, fungi, protozoa, or helminths. Despite intensive investigation, the cause of many episodes of encephalitis is unknown.

The most common known cause of encephalitis are viruses, accounting for around 70% of cases diagnosed.

The three most common causes of viral encephalitis are:

  • West Nile Virus
  • Herpes Simplex Virus
  • Enteroviruses

Dengue, rabies, western equine virus, rubella, cytomegalovirus, measles, mumps, varicella-zoster virus, and Epstein-Barr virus are among some other viral agents which cause viral encephalitis.

The majority of people with viral encephalitis experience a complication-free recovery. Those with persistent symptoms experience attention difficulties, behavioural and speech issues, and/or memory loss. Rarely, patients may continue to exist in a vegetative state. Some children infected with WEE may have convulsions and behavioural problems.

In the aftermath of EEE, children may experience seizures, severe mental retardation, and different types of paralysis. Infection with the Zika virus during pregnancy may be connected with microcephaly.

Seizures are the most prevalent long-term consequence following viral encephalitis, affecting 10-20% of individuals over decades. These convulsions are frequently resistant to medical treatment.

https://www.ncbi.nlm.nih.gov/books/NBK470162/